Temperature control of modern electronic equipment has always been a concern for anyone designing any system involving electronics. From portable devices to computing systems to automobiles, the operating temperature range of the system is always of concern.
With respect to systems that include an integrated circuit chip, most traditional design schemes involve either integrating a thermal monitor on the chip itself which will protect that chip from damage or, in a system environment, placing a separate temperature sensor somewhere on the PC board. Both of these approaches have limitations. The internal on chip temperature sensor simply responds to the localized heating of the die itself, however, if the temperature problem is being caused by some other device located on the PC board, the on-chip temperature sensor may take too long to respond based upon the board thermal resistance and therefore provide no thermal protection at all. The stand-alone temperature sensor is similarly limited by the thermal resistance on the PC board. The board designer must place the temperature sensor where the designer initially feels is the best location based upon experience in designing systems. However this methodology usually results in having to re-spin the PC board because, after being assembled and tested, the hot spots on the board are usually different from the original assumptions. This can lead to unnecessary expense and delay time in the project development. Furthermore, the hot spots on the PCB can further change when the PCB is enclosed in a system case with a fan and air vents for cooling the system. This can require the PCB to be yet again redesigned for proper placement of the temperature sensor.